What are the possible side effects of the flu vaccine?

Pain, redness and swelling at the injection site like any medication. Occasionally you may experience:

a low grade temperature

muscle aches

drowsiness or tiredness

a temporary small lump at the injection site

Most side effects are minor and last a short time, resolve without any treatment and do not lead to any long-term problems. Generally, mild reactions begin within six to 12 hours. As with any medication, very rarely there is the possibility of a severe allergic reaction which will usually occur within 15 minutes of receiving a vaccine. Hence stay in your GP’s surgery a short time after the injection to make sure all is ok.